When enabled, this pragma warns about indirect method calls that are present in your code.

The indirect syntax is now considered harmful, since its parsing has many quirks and its use is error prone : when the subroutine foo has not been declared in the current package, foo $x actually compiles to $x->foo, and foo { key => 1 } to 'key'->foo(1). Please refer to the "REFERENCES" section for a more complete list of reasons for avoiding this construct.

This pragma currently does not warn for core functions (print, say, exec or system). This may change in the future, or may be added as optional features that would be enabled by passing options to unimport.

Magically called when no indirect @opts is encountered. Turns the module on. The policy to apply depends on what is first found in @opts :

If it is a string that matches /^:?fatal$/i, the compilation will croak when the first indirect method call is found.

This option is mutually exclusive with the 'hook' option.

If the key/value pair hook => $hook comes first, $hook will be called for each error with a string representation of the object as $_[0], the method name as $_[1], the current file as $_[2] and the line number as $_[3]. If and only if the object is actually a block, $_[0] is assured to start by '{'.

This option is mutually exclusive with the 'fatal' option.

If none of fatal and hook are specified, a warning will be emitted for each indirect method call.

If @opts contains a string that matches /^:?global$/i, the pragma will be globally enabled for all code compiled after the current no indirect statement, except for code that is in the lexical scope of use indirect. This option may come indifferently before or after the fatal or hook options, in the case they are also passed to "unimport".

The global policy applied is the one resulting of the fatal or hook options, thus defaults to a warning when none of those are specified :

If this environment variable is set to true when the pragma is used for the first time, the XS code won't be loaded and, although the 'indirect' lexical hint will be set to true in the scope of use, the pragma itself won't do anything. In this case, the pragma will always be considered to be thread-safe, and as such "I_THREADSAFE" will be true. This is useful for disabling indirect in production environments.

Note that clearing this variable after indirect was loaded has no effect. If you want to re-enable the pragma later, you also need to reload it by deleting the 'indirect.pm' entry from %INC.

The implementation was tweaked to work around several limitations of vanilla perl pragmas : it's thread safe, and does not suffer from a perl 5.8.x-5.10.0 bug that causes all pragmas to propagate into required scopes.

Before perl 5.12, meth $obj (no semicolon) at the end of a file is not seen as an indirect method call, although it is as soon as there is another token before the end (as in meth $obj; or meth $obj 1). If you use perl 5.12 or greater, those constructs are correctly reported.

With 5.8 perls, the pragma does not propagate into eval STRING. This is due to a shortcoming in the way perl handles the hints hash, which is addressed in perl 5.10.

The search for indirect method calls happens before constant folding. Hence my $x = new Class if 0 will be caught.